Is it a special sign or it can be used as anything else? For creating variables for example.
$x=4 $\begingroup$ $\endgroup$
3 
1 Answer
$\begingroup$ $\endgroup$
3 $ is probably the only non-alphanumeric ascii character without a special meaning in Mathematica and thus the only one you could use as a delimiter for various parts within a variable name.
A warning is due: Because it is so unique, it is also used internally for the same purpose, e.g. Module and Unique will generate variable names ending in $+ an arbitrary integer:
Unique[] Module[{x},x] In some cases, also Function will generate variable names ending in $ for its arguments. You can read more about this here. To stay out of potential problems I would not use variables ending in $ or $ + integer.
Another case where $ seems to be used as some kind of internal convention are symbols which serve as global variables like $FrontEnd,$Context, $Path ..., but you can avoid conflicts by using a lowercase letter for the second letter of the variable name.
Other than the mentioned cases, I wouldn't expect problems when using $ within variable names. It should be mentioned that due to the possibility to use non-ascii letters within variable names, people often use such characters for similar purposes, e.g.:
long\[Bullet]name which will look nicer in the frontend, but won't render nice in the Wolfram Workbench editor.
- $\begingroup$ @Ajasja: thanks for the link, I remember now that I read that once, but couldn't remember... $\endgroup$Albert Retey– Albert Retey2013-05-14 16:38:51 +00:00Commented May 14, 2013 at 16:38
- 1$\begingroup$ You're welcome. You were right. Using
$at the end of a name can cause problems:f = Function[{x}, Function[{y}, x + y]]; o2 = f[2 y$]; o1 = f[2 y]; {o1[a], o2[a]}$\endgroup$Ajasja– Ajasja2013-05-14 16:47:13 +00:00Commented May 14, 2013 at 16:47 - 1$\begingroup$ Here's another example of
Functionusing$internally, causing confusion to the user: mathematica.stackexchange.com/q/25563/5 $\endgroup$2013-05-20 21:58:28 +00:00Commented May 20, 2013 at 21:58
$MachineEpsilon, but you can certainly start your variables with a dollar sign. $\endgroup$